I want to make my alarm clock “smart”. I'm very new to this stuff, that is, the hardware side. The programming shouldn't present too many problems.

I’m currently experimenting with a simulator (http://circuits.io) and want to start with controlling the alarm’s buzzer with my Arduino.

I did some reading on transistors and this is what I came up with:

I’ve turned pin D3 to high and hooked it up to the base of a NPN transistor. I’m trying to run 1.5V through the transistor, but nothing happens. Any thoughts?

Circuit that I came up with.

  • To me it looks like you have your emitter and collector backwards? (but it's hard to tell from the picture, is it E B C? I think it should be C B E) – redstarcoder Jan 20 '17 at 16:27
  • Could you add your ground connection(s) in, please? as @redstarcoder says, it's hard to understand where you're going with it. Are you trying to put the buzzer on the collector or the emitter? – Mark Smith Jan 20 '17 at 16:32
  • I just registered to the website to check, the first NPN transistor I saw was in fact C B E. – redstarcoder Jan 20 '17 at 16:38
  • You need to connect the GND of the Arduino to the GND/- of the battery. In most application the transistor is placed after the load (buzzer). So + -- buzzer -- transistor -- -. But I don't think it matters in this case. But I have the feeling you can connect the buzzer directly to the Arduino by just adding a proper value resistor, to lower the voltage to around 1.5V. Where did you get the buzzer from? – Gerben Jan 20 '17 at 17:01
  • @ redstarcoder The transistor in the picture is C B E, so the buzzer is connected to the emitter -- I expected it to be E B C. So the buzzer is on the collector, that's correct, right? @ MarkSmith Grounding the Arduino surely helped a lot and indeed fixed my problem. @ Gerben The buzzer is inside my alarm clock, I'll need to open it up to measure the exact voltage and current it requires -- I'll do that and report back. – user2693053 Jan 20 '17 at 17:54

You simply need to ground the circuit. In row E on your breadboard just under where you connect the - of the battery, connect that to the ground pin on the UNO. This causes the buzzer to start working.

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